Hydrosilylation reactions of at least one compound (C) comprising at least one unsaturation in the presence of an organosilicon compound (O) comprising at least one hydrogen atom directly bound to a silicon atom (either at least one Si—H group or a hydrogen siloxane function) are considerably widespread in the silicone industry for accessing silanes and functionalized polysiloxanes and also for preparing silicone lattices obtained by cross-linking between polymethylhydrogen siloxanes and polymethylvinylsiloxane oils. These reactions are generally catalyzed by organometal complexes based on platinum according to a homogenous catalysis mechanism. Among the well known homogenous hydrosilylation catalysts, mention may be made of Karstedt's platinum of formula Pt2(DVTMS)3, wherein DVTMS represents divinyltetramethyldisiloxane. However, this type of catalyst has different drawbacks. On the one hand, it is relatively unstable and changes during the reaction by forming colloidal species of Pt(0), the size of which is not controlled, which lead to a coloration of the reaction medium and obtained oils ranging from yellow to black. On the other hand, the steps for removing the platinum are costly and the catalyst cannot be recycled. Therefore, there exists a benefit to access easily recyclable, performing, heterogeneous catalysts, for which the preparation, the application and the activity are reproducible, giving the possibility of continuously operating for hydrosilylation reactions.
Heterogeneous catalysts, notably based on platinum, for the hydrosilylation reaction are for example known from U.S. Pat. No. 7,038,001.
However, a non-negligible amount of the platinum, contained in these heterogeneous catalysts, may be sorted out and solubilized in the reaction medium, this is then referred to as platinum in a homogenous phase. This phenomenon has different drawbacks:                the solubilization of a portion of the platinum of the catalyst induces a variability of the activity of the catalyst and therefore problems of reproducibility of hydrosilylation reactions;        in the case of partial hydrosilylation, i.e. when the reaction medium at the end of the reaction still comprises compounds comprising at least one hydrogen atom directly bound to at least one silicone atom, the platinum which was solubilized in the reaction medium may catalyze secondary reactions when said reaction medium is left in air. This may notably be a dehydrogenation condensation reaction between the SiH units and water from air, this reaction is at the origin of gelling of the surface of the reaction medium and of evolvement of dihydrogen with the notable risks of explosion which ensue. Sorting out platinum in the reaction medium therefore generates stability problems upon storage and of safety of the media comprising Si—H groups.        
In order to limit sorting out of the metal nanoparticles in a homogenous phase in the reaction medium, it is known from the prior art how to have the catalyst before use be subject to a heat treatment step under a controlled atmosphere. However, this heat treatment step generally has the effect of reducing the catalytic activity of the catalyst.
Therefore there exists a benefit of providing a method for hydrosilylation of compounds comprising at least one unsaturation and of organosiloxane compounds applying a catalytic system in which metal nanoparticles are sufficiently supported, while remaining accessible to the reagents, so as not to be sorted out in a homogenous phase in the reaction medium.